EP0346487A1 - Numerical control apparatus - Google Patents
Numerical control apparatus Download PDFInfo
- Publication number
- EP0346487A1 EP0346487A1 EP89900324A EP89900324A EP0346487A1 EP 0346487 A1 EP0346487 A1 EP 0346487A1 EP 89900324 A EP89900324 A EP 89900324A EP 89900324 A EP89900324 A EP 89900324A EP 0346487 A1 EP0346487 A1 EP 0346487A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- processors
- axis
- processor
- control apparatus
- machining
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Images
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
- G05B19/408—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by data handling or data format, e.g. reading, buffering or conversion of data
- G05B19/4083—Adapting programme, configuration
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
- G05B19/414—Structure of the control system, e.g. common controller or multiprocessor systems, interface to servo, programmable interface controller
- G05B19/4141—Structure of the control system, e.g. common controller or multiprocessor systems, interface to servo, programmable interface controller characterised by a controller or microprocessor per axis
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
- G05B19/414—Structure of the control system, e.g. common controller or multiprocessor systems, interface to servo, programmable interface controller
- G05B19/4144—Structure of the control system, e.g. common controller or multiprocessor systems, interface to servo, programmable interface controller characterised by using multiplexing for control system
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/30—Nc systems
- G05B2219/33—Director till display
- G05B2219/33125—System configuration, reconfiguration, customization, automatic
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/30—Nc systems
- G05B2219/33—Director till display
- G05B2219/33128—Different spindles, axis controlled by configured paths, channel
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/30—Nc systems
- G05B2219/33—Director till display
- G05B2219/33168—Two bus, master bus and local servo bus
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/30—Nc systems
- G05B2219/33—Director till display
- G05B2219/33337—For each axis a processor, microprocessor
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/30—Nc systems
- G05B2219/34—Director, elements to supervisory
- G05B2219/34013—Servocontroller
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
- Y02P90/02—Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]
Definitions
- an object of the present invention is to provide a flexible, extendible numerical control apparatus for controlling a variety of NC machine tools having a plurality of independently operable machining stations.
- a plurality of processors for numerical control are connected, via a first common bus, to a CRT/MDI unit, NC machining program supply means and a programmable controller for controlling a machine magnetics sequence, these units are made to share each of the processors, each processor and a plurality of axis controllers are connected to a second common bus, and each processor is caused to use exclusively a predetermined axis controller to control machining stations connected to the axis controllers.
- Numerals 41a - 41c denote first through third axis controllers, and 61a - 63c represent servomotors or spindle motors.
- Each of the axis controllers 41a - 41c is constituted by a pulse interpolator and a servo circuit provided for each axis, and the axis controllers are arranged so as to be capable of controlling the rotation of predetermined ones of the motors 61a - 63c connected thereto.
- the number of juxtaposed processors and ⁇ the number of juxtaposed axis controllers can be increased or decreased in conformity with the arrangement of the machine tools to be controlled, and the configuration is both flexible and extendible. That is, if the system involving an axis (limited to one axis) related to a single machining station is referred to as a channel, then the arrangement is such that a processor is capable of controlling one or more channels.
- the number of installed processors, the number of installed axis controllers and the number of motors are decided in dependence upon the number of channels of machine tools.
- a machine tool having a plurality of machining stations can be controlled by a single numerical control apparatus makes it possible to perform centralized management and control at one location. This facilitates operability without any decline in performance.
Landscapes
- Engineering & Computer Science (AREA)
- Human Computer Interaction (AREA)
- Manufacturing & Machinery (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Numerical Control (AREA)
Abstract
One or more processors (11a to 11c) for controlling machining stations having one or more shafts are arranged. The number of processors depends upon the constitution of the machine tool, and these processors are connected via first common bus (31) to a CRT and MDI unit (21), NC machining program supply means (22, 24), and programmable controller (23) that controls power sequence of the machine. These units are commonly used by the processors. Further, the processors (11a to 11c) are connected to shaft control units (41 a to 41 c) via a second common bus (51) so that each of the processors can exclusively use a predetermined shaft control unit through which the corresponding machining station is controlled.
Description
- This invention relates to a numerical control apparatus and, more particularly, to a flexible, extendible numerical control apparatus for controlling a variety of NC machine tools having a plurality of independently operable machining stations.
- When numerically controlling an NC machine tool having a plurality of independently controllable machining stations, such as a simultaneous four-axis lathe having two tool rests or other types of compound machines, conventionally control is performed by providing a plurality numerical control apparatus or by specially designing a numerical control apparatus dedicated to machine tools.
- However, the problem of high cost is encountered with the system for exercising control by providing a plurality of numerically control apparatus. With the method in which a special-purpose numerical control apparatus is designed, the hardware and software must be designed on each occasion, resulting in poor efficiency, and personnel and labor are required. The end result is high cost.
- Accordingly, an object of the present invention is to provide a flexible, extendible numerical control apparatus for controlling a variety of NC machine tools having a plurality of independently operable machining stations.
- In the numerical control apparatus of the present invention, a plurality of processors for numerical control are connected, via a first common bus, to a CRT/MDI unit, NC machining program supply means and a programmable controller for controlling a machine magnetics sequence, these units are made to share each of the processors, each processor and a plurality of axis controllers are connected to a second common bus, and each processor is caused to use exclusively a predetermined axis controller to control machining stations connected to the axis controllers.
-
- Fig. 1 is a block diagram of a numerical'control apparatus according to the present invention, and
- Fig. 2 is a system configuration diagram for a case where the present invention is applied to a simultaneous four-axis lathe equipped with a C axis.
- Fig. 1 is a block diagram of a numerical control apparatus according to the present invention.
- Numerals lla, llb, llc denote first, second and third processors for numerical control, one of which, say, the first processor lla, executes numerical control processing and serves to effect adjustment in such a manner that the entirety functions organically. It is permissible to separately provide a processor having such a supervisor-type function.
- Numeral 21 denotes a CRT/MDI unit in which a graphic display device and a manual data input device having various keys are arranged in integrated fashion. Numeral 22 denotes a memory storing an NC machining program, 23 a programmable controller (PMC unit) for controlling a machine magnetics sequence, 24 a tape reader for reading the machining program from an NC tape and storing the program in the
memory 22, 25 a RAM for storing data, and 31 a first common bus. - The processors lla - llc are connected to the units 21 - 25 via the first
common bus 31, and the units 21 - 25 are commonly connected to each of the processors. Thecommon bus 31 is dedicated to the first processor in accordance with predetermined standards by the bus control function of the first processor, and this processor is capable of accessing or utilizing each of the units. For example, it is so arranged that each processor can monopolize the bus in time sharing fashion or in a requested generation sequence. Exchange of data among processors takes place via theRAM 25. -
Numerals 41a - 41c denote first through third axis controllers, and 61a - 63c represent servomotors or spindle motors. Each of theaxis controllers 41a - 41c is constituted by a pulse interpolator and a servo circuit provided for each axis, and the axis controllers are arranged so as to be capable of controlling the rotation of predetermined ones of themotors 61a - 63c connected thereto. - The processors lla - 11c are connected to the
axis controllers 41a - 41c via a secondcommon bus 51, and each processor makes exclusive use solely of the axis controller assigned to it. The arrangement is such that when a processor is designated, exclusive use can be made of any of the axis controllers. Thecommon bus 51 is successively monopolized by the processors in, e.g., time-shared fashion, in accordance with predetermined standards by the bus control function of the first processor, and each processor is capable of making exclusive use solely of the axis controller assigned to it. - The number of juxtaposed processors and `the number of juxtaposed axis controllers can be increased or decreased in conformity with the arrangement of the machine tools to be controlled, and the configuration is both flexible and extendible. That is, if the system involving an axis (limited to one axis) related to a single machining station is referred to as a channel, then the arrangement is such that a processor is capable of controlling one or more channels. The number of installed processors, the number of installed axis controllers and the number of motors are decided in dependence upon the number of channels of machine tools.
- For example, the minimum apparatus configuration has one processor, one axis controller and the required number of motors, as indicated by the solid line in Fig. 1. However, as will be described below, the configuration of a numerical control apparatus for a simultaneous four-axis lathe equipped with a C axis can have its number of processors and its number of axis controllers increased or decreased, as shown in Fig. 2.
- Accordingly, with this apparatus, the number of processors and the number of axis controllers are decided in dependence upon the machine tool arrangement, a printed circuit board having processors which incorporate software peculiar to machine tools as well as axis controllers mounted thereon is inserted into a printed circuit board receptacle of an NC apparatus or an unnecessary printed circuit board is extracted, thereby making it possible to control a variety of machine tools.
- Fig. 2 shows an example of the arrangement of a numerical control apparatus according to the present invention for controlling a simultaneous four-axis lathe having a C axis. Portions similar to those shown in Fig. 1 are designated by like reference characters.
- In a simultaneous four-axis lathe having a C axis, (i) first and second NC machining programs having a queuing command are provided, and a workpiece is subjected to machining by controlling the movement of corresponding first and second tool rests in accordance with the first and second NC machining programs while synchronization is achieved by the queuing commands, and (ii) the workpiece is subjected to drilling or grooving by positionally controlling the workpice in the direction of rotation (in the C-axis direction). More specifically, the simultaneous four-axis lather equipped with a C axis is constituted by five axes, namely X, Z axes for controlling the movement of the first tool rest, X, Z axes for controlling the movement of the second tool rest, and the C axis. Let the X, Z axes for the first tool rest be a first channel, the C axis a second channel, and the X, Z axes for the second tool rest a third channel.
- Accordingly, the first processor lla for controlling the first and second channels and the second processor llb for controlling the third channel are provided, and the
first axis controller 41a for controllingaxis motors 61a - 61c of the first and second channels and the second axis controller 4lb for controllingaxis motors 62a, 62b of the third channel are provided. - A first NC machining program Pl for controlling the first and second channels and an NC machining program P2 for controlling the third channel are stored in the
memory 22. A function is provided for mutually queuing execution of the NC machining programs Pl, P2 between the first and second processors lla, llb by a queuing command. - Under these conditions, the apparatus of Fig. 2 is made to function as a numerical control apparatus for a simultaneous four-axis lathe equipped with a C axis if, by suitable means such as the CRT/
MDI unit 21, thefirst axis controller 41a is assigned to the first processor lla, thesecond axis controller 41b is assigned to the second processor llb, the first NC machining program Pl is assigned to the first processor lla and the second NC machining program P2 is assigned to the second processor llb. - In accordance with the present invention as described above, the arrangement of the apparatus is such that processors and axis controllers can be freely increased or decreased in number in dependence upon the size of the machine tool. Therefore, a variety of machine tools having a plurality of independently operable machining stations can be controlled by a single numerical control apparatus. Accordingly, it is unnecessary to design hardware for each and every machine tool and, by providing the software with universality, design changes can be eliminated or reduced.
- Further, in accordance with the invention, the fact that a machine tool having a plurality of machining stations can be controlled by a single numerical control apparatus makes it possible to perform centralized management and control at one location. This facilitates operability without any decline in performance.
- Furthermore, since the processors are bus-connected, the queuing of command programs between channels can be readily controlled, and the arrangement is such that the axis controllers are connected to the processors via a separate bus. As a result, there is no decline in performance due to bus contention.
- Still further, since the number of motors assigned to each channel can also be set freely depending upon the machine tool, the result is a flexible, inexpensive system configuration.
Claims (3)
1. A numerical control apparatus which has a display unit, a manual data input unit, NC machining program supply means and a programmable controller for controlling a magnetics sequence of a machine, and which is for numerically controlling a machining station composed of one or more axes via an axis controller, characterized by comprising:
processors, of which one or more are provided in conformity with a machine tool arrangement, for numerically controlling respective ones of one or a plurality of machining stations;
a first common bus connecting the processors and connecting the display unit, manual data input unit, NC machining program supply means and programmable controller;
axis controllers, of which one or more are provided in conformity with the machine tool arrangement, for driving the machining stations by commands from respective ones of the processors; and
a second common bus connecting the processors and connecting one or more axis controllers used exclusively by the processors.
2. A numerically control apparatus according to claim 1, characterized in that one processor among said processors is provided with a bus control function for allowing the first and second common buses to be dedicated to a predetermined processor.
3. A numerically control apparatus according to claim l, characterized in that the manual data input unit is provided with a function for specifying a correlation between a processor and the axis controller used exclusively by said processor.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP62332127A JPH01173204A (en) | 1987-12-28 | 1987-12-28 | Numerical controller |
JP332127/87 | 1987-12-28 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0346487A1 true EP0346487A1 (en) | 1989-12-20 |
EP0346487A4 EP0346487A4 (en) | 1992-10-28 |
Family
ID=18251454
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19890900324 Withdrawn EP0346487A4 (en) | 1987-12-28 | 1988-12-13 | Numerical control apparatus |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0346487A4 (en) |
JP (1) | JPH01173204A (en) |
KR (1) | KR920006161B1 (en) |
WO (1) | WO1989006390A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0362398A1 (en) * | 1988-02-26 | 1990-04-11 | Fanuc Ltd. | Numeric control unit for multiple-spindle and multiple-system machine tool |
EP0404939A1 (en) * | 1988-03-09 | 1991-01-02 | Fanuc Ltd. | Numerical controller |
US5252899A (en) * | 1988-03-09 | 1993-10-12 | Fanuc Ltd | Numerical control system |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0189757A1 (en) * | 1985-01-22 | 1986-08-06 | Siemens Aktiengesellschaft | Control device for a multiple-axle machine tool |
EP0103714B1 (en) * | 1982-09-07 | 1989-10-25 | General Electric Company | Multi-processor axis control |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS60218113A (en) * | 1984-04-13 | 1985-10-31 | Mitsubishi Electric Corp | Robot control system |
JPS61117605A (en) * | 1984-11-14 | 1986-06-05 | Hitachi Ltd | Robot control method |
JPS6277609A (en) * | 1985-10-01 | 1987-04-09 | Fanuc Ltd | Numerical controller with digital servo system for motor driving |
-
1987
- 1987-12-28 JP JP62332127A patent/JPH01173204A/en active Pending
-
1988
- 1988-12-13 EP EP19890900324 patent/EP0346487A4/en not_active Withdrawn
- 1988-12-13 WO PCT/JP1988/001263 patent/WO1989006390A1/en not_active Application Discontinuation
- 1988-12-13 KR KR1019890701605A patent/KR920006161B1/en not_active IP Right Cessation
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0103714B1 (en) * | 1982-09-07 | 1989-10-25 | General Electric Company | Multi-processor axis control |
EP0189757A1 (en) * | 1985-01-22 | 1986-08-06 | Siemens Aktiengesellschaft | Control device for a multiple-axle machine tool |
Non-Patent Citations (1)
Title |
---|
See also references of WO8906390A1 * |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0362398A1 (en) * | 1988-02-26 | 1990-04-11 | Fanuc Ltd. | Numeric control unit for multiple-spindle and multiple-system machine tool |
EP0362398A4 (en) * | 1988-02-26 | 1993-03-17 | Fanuc Ltd | Numeric control unit for multiple-spindle and multiple-system machine tool |
EP0404939A1 (en) * | 1988-03-09 | 1991-01-02 | Fanuc Ltd. | Numerical controller |
EP0404939A4 (en) * | 1988-03-09 | 1992-09-02 | Fanuc Ltd | Numerical controller |
US5252899A (en) * | 1988-03-09 | 1993-10-12 | Fanuc Ltd | Numerical control system |
Also Published As
Publication number | Publication date |
---|---|
WO1989006390A1 (en) | 1989-07-13 |
JPH01173204A (en) | 1989-07-07 |
KR920006161B1 (en) | 1992-07-31 |
KR900700942A (en) | 1990-08-17 |
EP0346487A4 (en) | 1992-10-28 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP0103714B1 (en) | Multi-processor axis control | |
US5252899A (en) | Numerical control system | |
US4606001A (en) | Customized canned cycles for computer numerical control system | |
EP0362398A1 (en) | Numeric control unit for multiple-spindle and multiple-system machine tool | |
EP0407589B1 (en) | Nc instruction system | |
JP2534305B2 (en) | Numerical control unit | |
EP0397886A1 (en) | Cnc control system | |
EP0389627A1 (en) | Interrupt control circuit for a multi-master bus | |
EP0346487A1 (en) | Numerical control apparatus | |
EP0351437A1 (en) | Cnc control system | |
US5359270A (en) | Numerical control system | |
EP0328663A4 (en) | Method of replacing the tools | |
US5060163A (en) | Programming apparatus for lathes | |
JP4255090B2 (en) | Numerical control device for machine tools | |
JP2875801B2 (en) | DNC equipment | |
Stute et al. | The application of a modular multiprocessor NC system | |
EP0553349A4 (en) | Cnc system for controlling a plurality of machines | |
EP0439618B1 (en) | Coordinative operation system of cnc | |
KR920005254B1 (en) | Numerical controller | |
JPS63312042A (en) | Tool interference preventing apparatus in numerically controlled automatic lathe | |
EP0380685A1 (en) | Nc command system | |
EP0090532A1 (en) | A composite NC input/output equipment | |
Inaba | Automation of a Machine Factory using CNC's with Large-Capacity Bubble Memories and a Robot | |
Becker | Development and Present Level of Numerical Controls | |
JPH03212707A (en) | Speed clamping control system |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 19890913 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): CH DE FR GB IT LI |
|
A4 | Supplementary search report drawn up and despatched |
Effective date: 19920910 |
|
AK | Designated contracting states |
Kind code of ref document: A4 Designated state(s): CH DE FR GB IT LI |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 19921218 |